Fix for possible endless lock in CLSM

gistfile1.diff

diff --git a/src/java/org/apache/cassandra/db/commitlog/CommitLogSegmentManager.java b/src/java/org/apache/cassandra/db/commitlog/CommitLogSegmentManager.java
index 4275362..815616b 100644
--- a/src/java/org/apache/cassandra/db/commitlog/CommitLogSegmentManager.java
+++ b/src/java/org/apache/cassandra/db/commitlog/CommitLogSegmentManager.java
@@ -288,10 +288,9 @@ public class CommitLogSegmentManager
         advanceAllocatingFrom(last);
 
         // flush and wait for all CFs that are dirty in segments up-to and including 'last'
-        Future<?> future = flushDataFrom(segmentsToRecycle);
         try
         {
-            future.get();
+            FBUtilities.waitOnFutures(flushDataFrom(segmentsToRecycle));
 
             // now recycle segments that are unused, as we may not have triggered a discardCompletedSegments()
             // if the previous active segment was the only one to recycle (since an active segment isn't
@@ -301,7 +300,7 @@ public class CommitLogSegmentManager
                     recycleSegment(segment);
 
             CommitLogSegment first;
-            assert (first = activeSegments.peek()) == null || first.id > last.id;
+            assert (first = activeSegments.peek()) == null || first.id > last.id : "first " + first.id + " <= last " + last.id;
         }
         catch (Throwable t)
         {
@@ -443,7 +442,7 @@ public class CommitLogSegmentManager
      *
      * @return a Future that will finish when all the flushes are complete.
      */
-    private Future<?> flushDataFrom(Collection<CommitLogSegment> segments)
+    private Collection<Future<?>> flushDataFrom(Collection<CommitLogSegment> segments)
     {
         // a map of CfId -> forceFlush() to ensure we only queue one flush per cf
         final Map<UUID, Future<?>> flushes = new LinkedHashMap<>();
@@ -479,14 +478,7 @@ public class CommitLogSegmentManager
             }
         }
 
-        return new FutureTask<>(new Callable<Object>()
-        {
-            public Object call()
-            {
-                FBUtilities.waitOnFutures(flushes.values());
-                return null;
-            }
-        });
+        return flushes.values();
     }
 
     /**